(a) Field of the Invention
The present invention concerns a breathing gas feeding device, more particularly for scuba diver, of the type comprising a housing defining an internal chamber bound by a flexible diaphragm, an expansion valve unit disposed in a first lateral wall of the housing and comprising a valve cooperating with a seat and unitary with a piston at a first end of a piston rod unit extending into the internal chamber and whose other end is coupled to a lever cooperating with the diaphragm.
(b) Description of Prior Art
A device of this type is described in the document FR-A-2.644.750, in the name of the Applicant. This type of device enables, through the diaphragm, a user to be able to rely on sufficient quantities of breathable gas and at the pressure of the surrounding medium, the expansion valve unit ensuring the required expansion of the breathing gas, which is supplied at a pressure higher than that of the surrounding medium. As mentioned in the above document, such an expansion results in a production of cold which is quite important in the housing, thus tending to substantially cool the mechanical control train of the valve unit. When the user operates in a surrounding at cold temperature, the temperature in the internal chamber goes down to a still lower value. The internal chamber often contains water, which penetrates therein through the breathing mouth piece. Moreover, the air which is exhaled by the user is saturated with humidity. The humidity which is present in the chamber is converted into ice upon contact with cold pieces, which may cause a blocking of the mechanical train of the valve unit. According to a first possibility enabling to overcome these disadvantages, the above document suggested to provide the rod assembly in a non-heat conductive material. The actual tendency being to produce the housings not with a metal but with a plastic material, the solution according to the first suggestion mentioned above was found to be insufficient.